Apparatus for preventing printing of zeros above the highest order of a printed number

ABSTRACT

A slide moving toward the lowest order of an ordinal series of digital printing elements, carries a coupling feeler which is displaced by the printing element of the highest order of a number represented by the printing elements, to couple the slide with stationary arresting means so that the slide is stopped in a position in which a control means thereof separates the printing elements of orders above the highest order of the number, from other printing means so that no zeros are printed by the printing elements of orders above the highest order of the printed number.

United States Patent Thevis et al.

[54] APPARATUS FOR PREVENTING PRINTING 0F zERos ABOVE THE HIGHEST ORDER OF A PRINTED NUMB R [72] Inventors: Paul Thevis, Oberndorf; Adolf Schneider, Altoberndort, both of Germany [73] Assignee: Olympia 'Wereke A.G., Wilhelmshaven, Germany Filed: 'June 22,1971 2n Appl.No.: 155,468

[30] Foreign Application Priority Data June 23, 1970 Germany ..P 20 36 548.4 1

52 us. CL; "1235/6028, 235/60 P, 101/93 R 51 Im. Cl. ..G06c 11/04 [58] Field of Search, ..235/60.28 60.25, 60 P;

* Sept. 26, 1972 [56] References Cited UNITED STATES PATENTS 3,221,644 12/1965 Gelling ..l0l/93 R 3,241,756 3/1966 Schenk ..235/60.28 3,260,449 7/1966 Gassino ..235/60.25 3,637,987 1/1972 Rauch ..235/60.28

Primary Examiner-Stephen J Tomsky A!t0rneyMichael S. Striker I 571 I ABSTRACT A slide moving toward the lowest order of an ordinal series of digital printing elements, carries a coupling feeler 'which is displaced by the printing element of I the highest order of a number represented by the printing elements, to couple the slide with stationary arresting means so that the slide is stopped in a position in which a control means thereof separates the printing elements of orders above the highest order of the number, from other printing means so that no zeros are printed by the printing elements of orders 'above the highest order of the printed number.

10 Claims, 6 Drawing Figures PAIENTEDssrzs 1912 3.693.871

sum 2 0F 3 INVENTOR PA Uh THE I15 ,4 m; am/510a PATENTEDsms m2 3693.871

SHEET 3 0! 3 Fig.5 39 Q 37 37 INVENTOR Pfiuu rm, now Sc/mewe APPARATUS FOR PREVENTING PRINTING OF ZEROS ABOVE THE HIGHEST ORDEROF A PRINTED NUMBER BACKGROUND OF THE INVENTION The present invention is concerned with an improvement of apparatus in which a movable slide prevents the printing of zeros above the highest order of a printed number. In a known apparatus serving this purpose, disclosed in the U.S. Pat. No. 3,241,756 the printing of zeros above the highest order of printed numbers is prevented by a slide which locks spring-biassed printing hammers so that the same cannot effect imprints. The spring-biassed slide frictionally engages the type carrier of the highest order of the printed number, and brakes its movement to the printing position, so that the type carrier of the highest order of the number, produces a weak imprint, or no imprint at all. Another disadvantage of the prior art construction resides in that the slide, held in its initial position above the highest order of the type carriers, cannot be released without frictionally engaging the type carrier of the highest order so that even movement of the same to the selected digital position of the highest order of the number, is braked and obstructed.

SUMMARY THE INVENTION It is one object of the invention to provide an apparatus for preventing printing of zeros above the highest order of a printed number which does not cause frictional engagement and braking of the operating printing elements.

Another object of the invention is to provide an apparatus of simple construction which operates reliably even in high speed calculators, to prevent the printing of zeros above the highest order of a printed number.

Another object of the invention is to prevent a direct frictional engagement between a slide which blocks the printing elements of orders above the highest order of the number, with the printing element of the highest order. I

With these objects in view, a slide is provided with a movable feeler which engages the printing element of the highest order to be printed and is displaced by the same to arrest the slide, and simultaneously to release the printing element of the highest order of the number.

An embodiment of the invention comprises an ordinal row of digital printing elements having a normal zero position and other digital positions for representing a number having fewer orders than the ordinal row; slide means biassed to move in one direction along the row toward the printing element of the lowest order; spring-biassed feeler means mounted on the slide means for movement relative to the same and also for movement with the same along a path in which printing elements representing the number and having moved out of the zero position are located; stationary arresting means having an ordinal row of coupling portions; printing means cooperating with the printing elements in a printing position; and control means connected with the slide means for movement.

The feeler means engages during movement of the slide means the printing element of the highest order of the number and is displaced by the same relative to the slide means. The coupling portion correlated with the highest order of the number is engaged by the displaced feeler means so that further movement of the slide means with the feeler means causes coupling of the slide means with the stationary arresting means. In this manner, the slide is stopped in a position representing the highest order, while the displaced feeler means releases the printing element of the highest order permitting free movement of the same. Since the control means separate the printing elements of orders above the highest order of the number from the printing means when the slide means is stopped, no zeros are printed by the printing elements above the highest order.

In one embodiment of the invention the printing means include a platen, and the printing elements include type bars movable between digital positions. The control means include a control portion of the slide means blocking movement of the printing elements above the highest order of the number to the printing position.

In another embodiment of the invention, the slide means include a first slide mounting the feeler means and a second slide connected'with the first slide, and stopping with the same when the first slide is stopped by the feeler means engaging the arresting means. A control means includesa printing member secured to the second slide and located between pressure means and the printing elements. The printing member is placed by the second slide in a position to extend only between printing elements associated with the orders of the number and the pressure means. Consequently, the pressure means cannot produce imprints of the printing elements above the highest order of the number.

In both embodiments of the invention, the printing element of he highest order of the number is only momentarily engaged by the spring-biassed feeler means which is then coupled to the arresting means and displaced by the slide to a position releasing the printing element of the highest order. Consequently, friction between the slide or feeler and the printing element of the highest order cannot occur during the setting motion of the printing element or during the printing motion of the same. In the arrangement of the invention, the slide can be released from movement with the feeler means along the row of printing elements while the printing elements move to the first digital position following the zero position so that the printing speed without any danger of printing mistakes can be increased.

The principles of the invention an be applied to calculator having spring-biassed type bars movable in a rectilinear motion between the digital positions, and to rotary type wheels cooperating with a pressure member rocking in the direction of the line formed by the printing elements.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings- BRIEF DESCRIPTION OF THE DRAWING ing the apparatus of FIGS. 1 and 3 in another operational position;

FIG. 5 is a fragmentary schematic plan view illustrating a second embodiment of the invention; and

FIG. 6 is a fragmentary schematic side view of the embodiment of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to the embodiment of FIGS. 1 to 4, a row of printing elements is provided which include type bars 1 movable between a zero position and nine other digital positions representing the digits from I to 9. The type bars 1 from a row along the platen 8. Each type bar 1 has a longitudinal slot 2 in which a stud 4 at the end of one arm of an angular pressure lever 3 is located. The angular pressure levers 3 are mounted on ashaft 6 supported by housing walls 5, and are biassed by spring 7 to turn in clockwise direction for moving type bars 1 toward the platen 8.

A slide 9 is mounted on the housing walls 5 for movement parallel to the platen and along the row of printing elements 1, 3. Slide 9 has an initial position in which it is held by a locking member 11 engaging a corresponding cutout lla in slide 9. When locking member 11 is'retracted during the operational cycle of the machine by conventional operating means, spring urges slide 9 to move in the direction toward the lowest order of the printing elements 1, 3. Slide 9 has a projecting control portion 12 followed by a recessed portion. In the initial position of slide 9 shown in FIG. 1, the end portions 13a of all pressure levers 3 are located in the region of the cutout 12a, so that all pressure levers 3 can be turned by springs 7 to a position moving the respective type bars 1 toward the platen 8. In the position of FIG. 4, the control portion 12 prevents movement of the pressure member 3 of the highest order out of the position shown in FIG. 2, so that no imprint can be made by the respective type bar 1 Slide 9 carries a pivot 15 on which a feeler means in the form of a double-armed lever 14 is mounted for angular movement. One arm of feeler means 14 ends in a feeler portion 16 which cooperates with the type bars 1, and the other arm has a coupling portion 17 which extends substantially tangential to a circle having its center in the axis of pivot 15. A spring 19 connects feeler lever 14 with a stud 190 on slide,9 and urges feeler lever 14 to the initial position shown in FIG. 1 abutting a stop 20 secured to slide 9.

An arresting means 18, including a plate 18a having coupling recesses 22, and a transverse portion 21 secured by rivets 21a to the housing wall 5, cooperates with coupling portion 17 of feeler lever 14. The

coupling recesses 22 are respectively associated with decimal orders, and are also positioned substantially tangential to the circle having its center in pivot 15, so that the coupling portion 17 can slide into each of the coupling recesses of arresting means 18.

The apparatus shown in FIGS. 1 to 4 operates as follows:

When the operating means of the calculator, not shown, release all type bars 1, springs la pull the type bars out of the normal zero position to a digital position determined by the input of the calculator. It is assumed that the number represented by the type bars 1 has a number of orders which is one less than the total number of printing elements 3,1 provided in the machine. Consequently, the last type bar 1b remains in the initial zero position, while the type type bar 10, associated with the highest order of the selected number, and all other type bars 1, begin to move toward the respective selected digital positions.

When the type bar 1c of the highest order of the number has moved to the first digital position following the zero position, it is located in the path of movement of the feller portion 16 of feeler means 14. Type bar 1b of the highest order of the calculator, is in its zero position, and consequently not located in the path of movement of feelerportion 16.

When the type bars 1, with the exception of type bar lb, have moved to the digital position associated with digit 1, the operating means of the calculator, not shown, continuing the cyclical operation, retract the locking member 11 from the recess 11a in slide 9, so that a spring 10 moves slide 9 to the position shown in FIG. 3, in which feeler portion 16 abuts type bar 10 so that the continued movement of slide 9 causes turning of feeler lever 14 in counterclockwise direction about pivot 15 so that the coupling portion 17 of feeler lever 14 just enters the coupling recess 22c associated with the type bar 10, and with the highest order of the selected number.

Due to the continued movement of the slide 9, feeler lever 14 is turned to the position shown in FIG. 4 in which coupling portion 17 completely moves into coupling recess 220 of arresting means 18, while the feeler portion 16 of feeler lever 14 moves away from type bar 1c of the highest order of the number. Since coupling portion 17 in coupling recess 22c firmly couple feeler lever 14 with the stationary arresting means 18, slide 9 cannot further move and stops in the position shown in FIG. 4. Type bar 10 can further move, if required, to the selected digital position without being engaged or frictionally braked by the feeler portion 16 of feeler lever 14. It will be seen that type bar 1c is only momentarily engaged by the feeler portion 16 of the spring-biassed feeler lever 14, and otherwise is completely free to move to any selected digital position.

Slide 9 is now stopped in a position in which the projecting control portion 12 of slide 9 is located opposite I the end portion 13a of pressure lever 3 associated with the type bar lb of the highest order of the calculator, while the recessed portion 12a of slide 9 extends along all other pressure levers 3, which are associated with the type bars 1 representing the selected number.

During the following conventional printing operation, the operating means of the calculator, not shown, release all pressure levers 3 for angular movement in clockwise direction as viewed in FIG. 2, but only the pressure levers 3 associated with the type bars 1 representing the selected number can turn in clockwise direction for moving the respective type bars 1 to a printing position engaging platen 8, whilethe pressure lever 13 associated with the type bar 1b, which had remained in the zero position, cannot move the type bar 1b to a printing position, since the respective pressure lever 13 is blocked by the control portion 12, as best seen in FIG. 4.

It is evident that if several printing elements 3,1 remain unused due to the fact that the selected number has fewer orders, all printing elements 3,1 above the printing elements 3, associated with the highest order of the number, will be blocked by control portion 12, andwill not move to a printing position, so that no zeros are'printed by the unused highest order or orders of the feeler elements 3, l of the calculator.

, After'printing of the number represented by the used orders of the printing elements 3, l, which are in no way braked or obstructedby the feeler. means l4, 16, or by slide 9, the operating means of thecalculator, not shown, actuate an arm 23 pivotally connected with slide9by a pivot 23a, to move slide 9 against the action of spring :10 to the initial'position shown in FIG. 1, in which. the locking member 11 resiliently snaps into recess 11a of slide 9, while spring 19 turns feeler means arresting plate 32a, irrespective of the angular displacement of slide 27 about shaft 29.

Within slide 34, a feeler means in the form of a feeler lever 37 is mounted for angular movement on a pivot 38. Feeler lever 37 has a feeler portion 39 cooperating with the printing element 24 positioned so that any printing element 24 turned, to the digital position associated with the digit 1 out of the zero position, is

tion 39, as shown in FIG. 6-. r

14 to the position shown in FIG. 1, abutting stop 20, i

while coupling portion 17 is retracted from the coupling recesses 22 of the arresting plate 18a of arresting means 18.

In the embodiment illustratedin FIGS. .5 and 6, an ordinal set of rotatable printing elements 24 is provided, each printing element 25 having ten types associated with the digitsO to 9. FIG. 6 shows a printing element 24 in an initial zero position in which the zero type 24a is located under an elongated printing located in the path of movement of the feeler portion 39. In the zero position of the printing elements 24, no portion of the same is located in the path of feeler por- The other arm of feeler lever 37'has a coupling portion cooperating with-the coupling'recesses'33 of the arresting plate 32a. A spring 41, connecting feeler lever 37 and slide 34, turns arresting lever ,37 to anormal position abutting a stop 42 on slide 34. A spring 43, connecting slide 34 with the stationary 'wall portion,

urges slide 34 to move with feeler lever 37 along arresting plate 32a.

The embodiment of FIGS. 5 and 6 is operated substantially as the embodiment'described with reference to FIGS. 1 to 4.

When those printingelements 24 which represent a selected number assume the respective digital positions, first the portion of each printing element 24 associated with the digit 1 moves into the path of movement of the feeler portion 39. During this setting movement due to the action of springs, not shown, biassing printing elements 24 to turn in he clockwise direction of the arrow in FIG.'6, slide 34 is released by the operating means of the calculator, not shown, and

face 25a can roll on printing member 28 to press the same against a selected type of each printing element 24. The pressure member 25 is crescent shaped, so that the ordinal printing elements are successively operative during a rocking movement of pressure member 25. This apparatus is not'an object of the present invention, and disclosed in a co-pending application Ser. No. 108,104, filed Jan. 20, 1971.

The printing member 28 is preferably made of rubber or any other elastic material, and is mounted on a slide 27 which is turnable about a shaft 29 mounted in two walls of a frame 26 which carries the rocking pressure member 25. One wall 26a of frame 26 has a cutout 30 engaging the portion 27a of slide 27 so that by angular displacement of frame 26 not only pressure member 25, but also slide portion 27 with printing member 28 are moved between an inoperative position, and a printing position. In the end position of slide 27 shown in FIG. 5, printing member 28 extends across all printing elements 24, except the printing element of the lowest order. The housing walls 31, see FIG. 5, carry an arresting means 32 with an arresting plate32a having ordinal coupling recesses 33 arranged in a saw tooth pattern. Arresting plate 32a slidable mounts a slide 34 for movement parallel to the row of printing elements starts movement along the arresting plate 32 due to the action of spring 43. In the inoperative condition of the apparatus, a locking member holds slide 34 in the initial position, and this locking member is released by the operating means of the calculator when the printing elements have moved out of the zero position. When the feeler portion 39 of arresting lever 37 abuts the printing element 24 of the highest order of the selected number while this printing element is still in the digital position representing the digit 1, arresting lever 37 turns about pivot 38 against the action of spring 41 in clockwise direction and engages with coupling portion 40 the corresponding ordinal'coupling recess 33 of the arresting plate 32. The order of the engaged coupling recess 33 corresponds to the order of the printing element 24 engaged by feeler portion 39, which is the highest order of the selected number, but not necessarily the highest order of all printing elements 24 of the calculator.

ing element 24 of the highest order of the selected number, as shown in chain lines in FIG. 5. All printing elements 24 associated with the selected number including the printing element associated with the highest order of the selected number can now further move to the selected digital position, without any frictional braking being caused by feeler portion 39.

During the movement of slide 34 under the action of spring 43 along the arrestingplate 32, the second slide 27, together with the printing member 28, has moved in i the same direction the same distance due to the coupling 34, 36 between slides 34 and 27. Consequently, when slide 34 is stopped by arresting plate 32a, as described above, printing member 28 is in a position, not shown, in which it is withdrawn from the printing elements of the unused orders above the orders of the selected number. When the frame 26 is moved downward together with'pressure member 25 and printing member 28, so that a sheet of paper and an ink carrier are pressed together between the types of printing elements 24 and printing member 28, the crescent shaped pressure member 25 is rocked in line direction for making imprints of the type representing all digits of the selected number.

Printing elements 24 of the orders above the highest order of the selected number do not cause an imprint, since the printing member 28 has moved to a position in which it is not located above the printing elements 24 of the orders above the highest order of the selectednumber. The printing elements 24 associated with the orders of the selected number are connected by printing member 28 with the rocking pressure member 25, so that the respective selected number is printed, while the printing elements 24 of the orders above the highest order of the number, are disconnected from pressure member 25, and cannot print zeros.

When the selected number has been printed, the operating means of the calculator, not shown, continue a cyclical operation during which an arm corresponding to arm 23 in FIGS. 1 to 4, is operated to'retum the slide 34 with slide 27 to the initial position shown in FIG. 5.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of apparatus for preventing printing of zeros above the highest order of a printed number, differing from the types described above.

While the invention has been described as embodied in an apparatus in which a feeler determines the highest order which is tobe printed so that the printing elements are not frictionally braked, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

' Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for variousapplications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

illustrated and What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

We claim:

1. Apparatus for preventing printing of zeros above the highest order of a printed number, comprising an ordinal row of digital printing elements having a normal zero position and other digital positions for representing a number having fewer orders than said ordinal row; slide means biassed to move in one direction along said row toward the printing element of the lowest order; spring biassed feeler means mounted on said slidemeans for movement relative to the same, and also for movement with the same in said one direction along a path in which printing elements representing the number and having'moved out of said zero position are located so that said feeler means engages during movement of the slide means the printing element of the highest order of the number and'is displaced by the same relative to said slide means; stationary arresting coupling portion correlated with said highest orderbeing engaged by said displaced feeler means so .that further movement of said slide means with said feeler means causes coupling of said slide means with said stationary arresting means whereby said slide means is stopped in a position representing said highest order, while said displaced feeler means releases said printing element of said highest order, permitting free movement of the same; printing means cooperating with said printing elements in a printing position for effecting imprints by said printing elements; and control means connected with said slide means for movement in said one direction and separating the printing elements of orders above said highest order of the number from said printing means when said slide means is stopped so that no zeros are printed by said printing elements above said highest order.

2. Apparatus as claimed in claim 1 wherein said printing means include a platen; wherein each printing element is spring biassed to move to a printing position abutting said platen; and wherein said control means includes a control portion of said slide means blocking movement of the printing elements above said highest order of the number to said printing position.

3. Apparatus as claimed in claim 1 wherein printing means include a platen; wherein each printing element includes a spring biassed type bar movable between said zero and other digital positions, a pressure member connected with said type bar, and a spring biassing said pressure member for moving said type bar to a printing position abutting said platen; and wherein said control means includes a projecting control portion of said slide means blocking movement of the pressure members above said highest order of said number so that the respective type bars cannot move to said printing position.

4. Apparatus as claimed in claim 1 wherein a portion of any printing element in the digital position following said zero position is located in said path.

5. Apparatus as claimed in claim 1 wherein said slide means include a pivot means mounting said feeler means for movement with said slide means in said direction, and for relative angular displacement, and a spring biassing said feeler means against angular displacement by said printing element of said highest order.

6. Apparatus as claimed in claim wherein said feeler means has first and second arms, said first arm being located in said path for engaging said printing element of said highest order, and said second arm having a coupling portion; and wherein said coupling portions of said arresting means are separated by ordinal coupling recesses, one of which is engaged by said coupling portion of said feeler means when said feeler means is displaced by said printing element of said highest order.

7.. Apparatus as claimed in claim 6 wherein said coupling recesses and said coupling portion of said feeler means extend substantially tangential to a circle having the center located in the axis of said pivot means.

8. Apparatus as claimed in claim 1 wherein said printing means include pressure means; wherein said slide means include a first slide mounting said feeler means, and a second slide connected with said first slide for movement in said one direction and stopping when said first slide is stopped by said feeler means engaging said arresting means; and wherein said control means include a printing member secured to said second slide and being located between said pressure means and said printing elements so that an imprint is made when said pressure means presses said printing member against said printing elements; and wherein said printing member extends only between printing elements associated with the orders of the number and said pressure means when said first and second slides are stopped by said feeler means and arresting means; so that said pressure means cannot produce imprints of the printing elements above said highest order of said number.

9. Apparatus as claimed in claim 8 comprising a shaft parallel with said one direction supporting said second slide for angular'movement for moving said printing member toward and away from said printing elements; and wherein said printing means further include a frame mounted for angular movement and supporting said shaft and said pressure means, said frame having a cutout engaging said printing member so that said printing member turns about said shaft when said frame moves. said pressure means toward and away from said printing elements.

10. Apparatus as claimed in claim 9, wherein said first slide has a post, and said second slide has a recess in which said post is located so that said first and second slides are connected for movement in said one direction, and so that said recess moves along said post during angular movement of said second slide about said shaft. 

1. Apparatus for preventing printing of zeros above the highest order of a printed number, comprising an ordinal row of digital printing elements having a normal zero position and other digital positions for representing a number having fewer orders than said ordinal row; slide means biassed to move in one direction along said row toward the printing element of the lowest order; spring biassed feeler means mounted on said slide means for movement relative to the same, and also for movement with the same in said one direction along a path in which printing elements representing the number and having moved out of said zero position are located so that said feeler means engages during movement of the slide means the printing element of the highest order of the number and is displaced by the same relative to said slide means; stationary arresting means having an ordinal row of coupling portions, the coupling portion correlated with said highest order being engaged by said displaced feeler means so that further movement of said slide means with said feeler means causes coupling of said slide means with said stationary arresting means whereby said slide means is stopped in a position representing said highest order, while said displaced feeler means releases said printing element of said highest order, permitting free movement of the same; printing means cooperating with said printing elements in a printing position for effecting imprints by said printing elements; and control means connected with said slide means for movement in said one direction and separating the printing elements of orders above said highest order of the number from said printing means when said slide means is stopped so that no zeros are printed by said printing elements above said highest order.
 2. Apparatus as claimed in claim 1 wherein said printing means include a platen; wherein each printing element is spring biassed to move to a printing position abutting said platen; and wherein said control means includes a control portion of said slide means blocking movement of the printing elements above said highest order of the number to said printing position.
 3. Apparatus as claimed in claim 1 wherein printing means include a platen; wherein each printing element includes a spring biassed type bar movable between said zero and other digital positions, a pressure member connected with said type bar, and a spring biassing said pressure member for moving said type bar to a printing position abutting said platen; and wherein said control means includes a projecting control portion of said slide means blocking movement of the pressure members above said highest order of said number so that the respective type bars cannot move to said printing position.
 4. Apparatus as claimed in claim 1 wherein a portion of any printing element in the digital position following said zero position is located in said path.
 5. Apparatus as claimed in claim 1 wherein said slide means include a pivot means mounting said feeler means for movement with said slide means in said direction, and for relative angular displacement, and a spring biassing said feeler means against angular displacement by said printing element of said highest order.
 6. Apparatus as claimed in claim 5 wherein said feeler means has first and second arms, said first arm being located in said path for engaging said printing element of said highest order, and said second arm having a coupling portion; and wherein said coupling portions of said arresting means are separated by ordinal coupling recesses, one of which is engaged by said coupling Portion of said feeler means when said feeler means is displaced by said printing element of said highest order.
 7. Apparatus as claimed in claim 6 wherein said coupling recesses and said coupling portion of said feeler means extend substantially tangential to a circle having the center located in the axis of said pivot means.
 8. Apparatus as claimed in claim 1 wherein said printing means include pressure means; wherein said slide means include a first slide mounting said feeler means, and a second slide connected with said first slide for movement in said one direction and stopping when said first slide is stopped by said feeler means engaging said arresting means; and wherein said control means include a printing member secured to said second slide and being located between said pressure means and said printing elements so that an imprint is made when said pressure means presses said printing member against said printing elements; and wherein said printing member extends only between printing elements associated with the orders of the number and said pressure means when said first and second slides are stopped by said feeler means and arresting means; so that said pressure means cannot produce imprints of the printing elements above said highest order of said number.
 9. Apparatus as claimed in claim 8 comprising a shaft parallel with said one direction supporting said second slide for angular movement for moving said printing member toward and away from said printing elements; and wherein said printing means further include a frame mounted for angular movement and supporting said shaft and said pressure means, said frame having a cutout engaging said printing member so that said printing member turns about said shaft when said frame moves said pressure means toward and away from said printing elements.
 10. Apparatus as claimed in claim 9, wherein said first slide has a post, and said second slide has a recess in which said post is located so that said first and second slides are connected for movement in said one direction, and so that said recess moves along said post during angular movement of said second slide about said shaft. 